<?php
class AdModel extends Model
{
	static public function getInstance()
	{
		static $Ad = null;
		if($Ad == null){
			$Ad = M('Ads');
		}
		return $Ad;
	}

	static public function getAdList($options)
	{
		$options['is_show'] = true;
		return self::getInstance()->where($options)->select();
	}
}